Deliberation and Voting in Approval-Based Multi-Winner Elections

TL;DR

This paper investigates how deliberation influences approval-based multi-winner voting outcomes, showing that deliberation generally improves welfare and representation, with simple voting rules performing well if properly supported.

Contribution

It introduces a deliberation model based on opinion dynamics and analyzes its impact on voting outcomes, highlighting the importance of deliberation organization.

Findings

Deliberation improves welfare and representation guarantees.

Simple approval voting performs comparably to more complex rules with proper deliberation.

The organization of the deliberation process significantly affects voting results.

Abstract

Citizen-focused democratic processes where participants deliberate on alternatives and then vote to make the final decision are increasingly popular today. While the computational social choice literature has extensively investigated voting rules, there is limited work that explicitly looks at the interplay of the deliberative process and voting. In this paper, we build a deliberation model using established models from the opinion-dynamics literature and study the effect of different deliberation mechanisms on voting outcomes achieved when using well-studied voting rules. Our results show that deliberation generally improves welfare and representation guarantees, but the results are sensitive to how the deliberation process is organized. We also show, experimentally, that simple voting rules, such as approval voting, perform as well as more sophisticated rules such as proportional approval voting or method of equal shares if deliberation is properly supported. This has ramifications on the practical use of such voting rules in citizen-focused democratic processes.